A multibeam feed for the Parkes radio-telescope

The Parkes radio-telescope is as busy as it ever was in its more than 30-year lifetime. To improve the telescope further, a multiple beam capability is being investigated. This would have considerable impact on a proposed detailed study of the southern sky in the frequency range 1.27 to 1.47 GHz. With the present, single, prime-focus feed, this would take about 10 years to complete, but by using multiple beams, each with two orthogonal linear polarizations, the survey time would be reduced to a more manageable observing period. A combination of reflector scan-gain loss, as the feeds are displaced from the focus, and the limited number of available correlator units, restricts a practical array to about nine elements which, nevertheless, gives a substantial order of magnitude reduction in observing time. We describe here a preliminary study of the Parkes antenna performance with a cluster of nine feed horns, where each horn in the cluster is responsible for two orthogonal linear polarizations within a beam.<>